DRRR

• With the Philippines along the so-called “Pacific Ring of Fire” volcanic hazards are present all-year round, especially in areas where volcanoes are still active, such as Mt. Mayon in Albay and Mt. Kanlaon in Negros Island
• Even though volcanoes have been studied by scientists, since they are natural systems, there is still the element of unpredictability of their activity
• There are signs that can be noted to minimize the damaging impact of volcanoes
• Examples of volcanic hazards

  • Lahar
  • Ash fall
  • Pyroclastic fall
  • Pyroclastic density current
  • Volcanic gases
  • Lava flow
• Lahar


  A specific kind of heavy mudflow made up of volcanic debris that can travel at speeds of over 80 kph rapidly covering wide swaths of land and is destructive since it can bury anything along its path
• Ash fall


  Generally does not directly endanger life but can have long-term effects, especially on the respiratory health of humans and on agriculture
• Pyroclastic fall


  Also called volcanic fallout, this consist of ejected rocks during a volcanic activity that fall to the ground and can affect agriculture and biodiversity surrounding a volcano, destroy engines and dent metals, scratch surfaces and break delicate objects
• Pyroclastic density current


  Made up of pulverized rock, ash and hot gases that can move at hundreds of kilometers per hour, can be of two types: surges (dilute) or flows (concentrated)
• Volcanic gases


  Some of the gases released in a volcanic eruption are water vapor (H2O), carbon dioxide (CO2), sulfur-based gases (SO2 and H2S), and fluorine-based gases (F2 and HF), S-based gases have acidic, rotten-egg smell that can irritate the eyes and nose, and can mix with water to form H2SO4, F-based gases are poisonous, corrosive and toxic
• Lava flow


  Made up of extremely hot molten rock and burns everything along its path
• With the lithosphere as one of the earth subsystems, it is inevitable that humans are affected by phenomena involving the lithosphere
• Many movements, changes and fragmentation that take place in the lithosphere present hazards
• Geological hazards


  • Earthquakes
  • Volcanoes
• Geological hazards in the Philippines

  • Rainfall-induced landslide and rock fall
  • Mudflows
  • Sinkholes
• Rainfall-induced landslide and rock fall


  Not only earthquakes can induce landslides and rock fall. Intense rainfall can trigger landslides, too.
• Mudflows


  If water accumulates under the ground in an elevated place (possibly in a crevice), mudflow may happen following heavy rainfall. Mudflows are different from landslides in that more water is present in mudflows.
• Sinkholes


  When a ground has no natural external surface drainage (meaning water cannot leak out on the surface), water will mainly stay on the subsurface. What happens is that this water will dissolve some of the rocks near it. As these rocks dissolve, empty spaces and caverns can be carved out of land masses. Sinkholes are then formed if the spaces formed underground are too wide to support the ground surface which sinks into the empty spaces.
• Signs of an area prone to sinkhole formation

  • Circular pattern of cracks outlining the sinking ground area
  • Vegetation stress or withering (due to a lower water table or level of underground water)
  • Long-term turbidity or cloudiness in local well water
• Other geological hazards in the world

  • Avalanches in elevated places with heavy snow
  • Sand storms in deserts